With the development of electronic technology, the number of types of electronic devices dramatically increases. The electronic devices are used for work, study, routine life and entertainment. As a result, large amount of user information is stored in the electronic devices. Such information may relate to information to be kept secret such as privacy, property, etc. Obviously, this involves information security. On the other hand, users can make payment by using the electronic devices. If the electronic devices are illegally possessed by other users, operations which may be harmful to the legal user's person, property, and credit security may be conducted. Therefore, usage security of the electronic devices is also of profound significance.
How to improve information security and usage security is a problem to be solved in utilization of the electronic devices.